Sphere Online Judge (SPOJ)

list of classical problems (unsolved)

ID	NAME	USERS	ACC %	DIFFICULTY C I
1704	Countdown	306	25.66	22 8
1705	The Game of Efil	91	50.00	1 1
1708	Square Count	75	30.98
1709	Swamp Things	290	40.40
1715	Another Necklace Problem	52	18.42	17 17
1722	Life, the Universe, and Everything II	68	28.49
1725	The Importance	101	38.54	17 17
1726	Exchange	24	7.92	50 34
1739	Yet Another Equation	237	41.51
1772	Find The Determinant II	102	30.63	1 50
1788	Fractan	50	30.63	17 17
1793	Text Generater II	57	30.59	17 17
1800	Fixed Partition Contest Management	63	36.99	17 1
1810	Nuclear Plants	22	11.90	17 17
1815	Problems Collection (Volume X)	77	7.26
1838	Ticket to Ride	91	41.94	17 34
1842	Lineland Airport	37	18.64
1877	Enrich my purse	153	27.01
1880	Hanoi Calls	205	54.44
1962	Circles	62	20.12
1963	Image Projections	109	34.26
1964	Tree cut	149	38.10
1966	Ski Valley	117	18.43
2002	Random Number Generator	98	40.62
2019	The Rolling Ball	4	5.48
2022	Truth Or Lie	104	21.17
2023	One Instruction Computer Simulator	47	10.58	42 42
2031	Please help You-Know-Who	39	28.65
2052	Hexagonal Parcels	76	28.93
2060	Tough Water Level	36	18.21
2070	Minimum Distance	86	16.85	17 1
2129	Cake	70	21.59
2130	Trolls	29	39.19
2132	Puzzle	89	32.68
2140	(un)Fair Play	75	38.08
2141	Golden Garden	17	12.20
2142	Arranging Flowers	25	9.87
2144	K Edge-disjoint Branchings	9	12.35
2147	Root of a Linear Equation	66	8.90	34 17
2151	Digital Calculator	23	5.69
2153	Internet is Faulty	69	38.54
2154	Kruskal	85	14.03
2159	Delicious Cake	30	14.64
2160	Here-There	30	24.76
2161	Pixel Shuffle	34	21.03	50 17
2162	Towers of Powers	26	13.87
2180	Justice League	83	48.97
2202	Tan and His Interesting Game	46	25.18
2270	Balloons in a Box	172	23.77
2271	Undecodable Codes	48	12.27